Mister Exam

Derivative of y=x^4cos2x

Function f() - derivative -N order at the point
v

The graph:

from to

Piecewise:

The solution

You have entered [src]
 4         
x *cos(2*x)
$$x^{4} \cos{\left(2 x \right)}$$
x^4*cos(2*x)
Detail solution
  1. Apply the product rule:

    ; to find :

    1. Apply the power rule: goes to

    ; to find :

    1. Let .

    2. The derivative of cosine is negative sine:

    3. Then, apply the chain rule. Multiply by :

      1. The derivative of a constant times a function is the constant times the derivative of the function.

        1. Apply the power rule: goes to

        So, the result is:

      The result of the chain rule is:

    The result is:

  2. Now simplify:


The answer is:

The graph
The first derivative [src]
     4               3         
- 2*x *sin(2*x) + 4*x *cos(2*x)
$$- 2 x^{4} \sin{\left(2 x \right)} + 4 x^{3} \cos{\left(2 x \right)}$$
The second derivative [src]
   2 /              2                        \
4*x *\3*cos(2*x) - x *cos(2*x) - 4*x*sin(2*x)/
$$4 x^{2} \left(- x^{2} \cos{\left(2 x \right)} - 4 x \sin{\left(2 x \right)} + 3 \cos{\left(2 x \right)}\right)$$
The third derivative [src]
    /              3                              2         \
8*x*\3*cos(2*x) + x *sin(2*x) - 9*x*sin(2*x) - 6*x *cos(2*x)/
$$8 x \left(x^{3} \sin{\left(2 x \right)} - 6 x^{2} \cos{\left(2 x \right)} - 9 x \sin{\left(2 x \right)} + 3 \cos{\left(2 x \right)}\right)$$
The graph
Derivative of y=x^4cos2x